Abstract: Until the end of the Eighties the maximum dredging depth of the moving suction dredgers known as «hoppers» was directly related to the maximum draughts of the ships. About the middle of the Nineties a new generation of hopper dredgers commonly called «JUMBO» came to the fore (capacity of 16.000 m3 up to more than 35.000 m3). The main branch of industry using these dredgers is the dredging and the transportation of big quantities of sand for the construction of large quay levels gained on the sea (particularly in the Middle and Far East).

This new generation of dredgers made it possible (thanks to the length of the ship’s hull) to install very long dredging ladders which allow for dredging at depths below 100 meters. This new situation permits the search and then the exploitation of sand pits at depths of 100 meters and more, thus making it possible to carry out projects of beaches recharging (coastal structure) by substantially limiting the impact on marine environment (the presence of marine vegetation usually stops at depths around 35 to 40 meters)

The implementation of such projects by using the Jumbo type dredgers allows also the exploitation of a submarine quarry in a much wider area (100 to 200 km between the extraction site and the backfilled area ) while remaining within acceptable economic limits.

The use of JUMBO dredgers is justified however only if the volumes at stakes are sufficient to recoup the expenses of site mobilization and installation, the traditional assignment area of this type of machine being indeed the Far and the Middle-East. So in order to make such intervention profitable, it is advisable to group various beach recharging operations (at the regional level for example) to attain a several million m3 operation. 

Key words:

Jumbo, deep Dredging, offshore deposits.